Principally there are two common ways of connecting a chip to a carrier like a printed circuit board, viz. wire or ribbon bonding and Flip chip bonding. In wire or ribbon bonding an interconnecting medium in the form of a small wire or ribbon is thermo-compression bonded at its edges to the chip and to a conductor of the electric circuit on the board, respectively. In Flip chip bonding a small solder “bump” is introduced as a connecting medium between the chip and the conductor of the electric circuit.
Thus the general way of interconnecting a chip and an electric circuit on a carrier according to the prior art consists in adding interconnecting material like wires, ribbons or solder bumps.
In wire or ribbon bonding reels of wire or ribbon are attached to a wire or ribbon bonder. Because of the bonding technology the interconnecting wire or ribbon will get a wave-shaped form with a number of curves up and down, as illustrated in FIG. 1. FIG. 1 shows a carrier 2, such as a printed circuit board, and a chip 4 mounted on a ground plate 6. On their upper sides in the figure, the carrier 2 and the chip 4 are provided with conductors 8 and 10 respectively which are interconnected with a wire or ribbon 12 exhibiting curves up and down, as mentioned above. Since the wire or ribbon 12 will not extend up to the edges of the conductors propagating microwaves will have to pass around the edges of the conductors to reach the wire or ribbon 12. This prolonged way for the microwave signals at the interconnection often result in a lacking signal adaptation with increased losses as a result.
The shape of the wire or ribbon 12 will normally be roughly the same at the conductor 8 on the carrier 2 and at the chip conductor 10, although an adapted shape would be preferred.